Automatically update the controller version (#57)

Create a new GitHub Actions workflow to submit a pull request for new controller versions.

.github/workflows/generate.yaml

@@ -0,0 +1,31 @@
+---
+on:
+  schedule:
+    - cron: "0 0 * * *"
+  workflow_dispatch: {}
+
+env:
+  GO_VERSION: "^1.16"
+
+jobs:
+  fields:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: "actions/setup-go@v2"
+        with:
+          go-version: "${{ env.GO_VERSION }}"
+
+      - uses: "actions/checkout@v2"
+      - uses: "actions/cache@v2"
+        with:
+          path: "~/go/pkg/mod"
+          key: "${{ runner.os }}-gomod-${{ hashFiles('**/go.sum') }}"
+          restore-keys: |
+            ${{ runner.os }}-gomod-
+
+      # TODO: Automatically merge the PR if tests pass.
+      - run: "go generate unifi/fields.go"
+      - uses: "peter-evans/create-pull-request@v3"
+        with:
+          delete-branch: true
+          title: "Update to latest controller version"